/*
 * A JavaScript implementation of the RSA Data Security, Inc. MD5 Message
 * Digest Algorithm, as defined in RFC 1321.
 * Version 1.1 Copyright (C) Paul Johnston 1999 - 2002.
 * Code also contributed by Greg Holt
 * See http://pajhome.org.uk/site/legal.html for details.
 */



/*
 * Add integers, wrapping at 2^32. This uses 16-bit operations internally
 * to work around bugs in some JS interpreters.
 */

function safe_add(x, y) {

  var lsw = (x & 0xFFFF) + (y & 0xFFFF)

  var msw = (x >> 16) + (y >> 16) + (lsw >> 16)

  return (msw << 16) | (lsw & 0xFFFF)

}



/*
 * Bitwise rotate a 32-bit number to the left.
 */

function rol(num, cnt) {

  return (num << cnt) | (num >>> (32 - cnt))

}



/*
 * These functions implement the four basic operations the algorithm uses.
 */

function cmn(q, a, b, x, s, t) {

  return safe_add(rol(safe_add(safe_add(a, q), safe_add(x, t)), s), b)

}

function ff(a, b, c, d, x, s, t) {

  return cmn((b & c) | ((~b) & d), a, b, x, s, t)

}

function gg(a, b, c, d, x, s, t) {

  return cmn((b & d) | (c & (~d)), a, b, x, s, t)

}

function hh(a, b, c, d, x, s, t) {

  return cmn(b ^ c ^ d, a, b, x, s, t)

}

function ii(a, b, c, d, x, s, t) {

  return cmn(c ^ (b | (~d)), a, b, x, s, t)

}



/*
 * Calculate the MD5 of an array of little-endian words, producing an array
 * of little-endian words.
 */

function coreMD5(x) {

  var a = 1732584193

  var b = -271733879

  var c = -1732584194

  var d = 271733878



  for (var i = 0; i < x.length; i += 16) {

    var olda = a

    var oldb = b

    var oldc = c

    var oldd = d



    a = ff(a, b, c, d, x[i + 0], 7, -680876936)

    d = ff(d, a, b, c, x[i + 1], 12, -389564586)

    c = ff(c, d, a, b, x[i + 2], 17, 606105819)

    b = ff(b, c, d, a, x[i + 3], 22, -1044525330)

    a = ff(a, b, c, d, x[i + 4], 7, -176418897)

    d = ff(d, a, b, c, x[i + 5], 12, 1200080426)

    c = ff(c, d, a, b, x[i + 6], 17, -1473231341)

    b = ff(b, c, d, a, x[i + 7], 22, -45705983)

    a = ff(a, b, c, d, x[i + 8], 7, 1770035416)

    d = ff(d, a, b, c, x[i + 9], 12, -1958414417)

    c = ff(c, d, a, b, x[i + 10], 17, -42063)

    b = ff(b, c, d, a, x[i + 11], 22, -1990404162)

    a = ff(a, b, c, d, x[i + 12], 7, 1804603682)

    d = ff(d, a, b, c, x[i + 13], 12, -40341101)

    c = ff(c, d, a, b, x[i + 14], 17, -1502002290)

    b = ff(b, c, d, a, x[i + 15], 22, 1236535329)



    a = gg(a, b, c, d, x[i + 1], 5, -165796510)

    d = gg(d, a, b, c, x[i + 6], 9, -1069501632)

    c = gg(c, d, a, b, x[i + 11], 14, 643717713)

    b = gg(b, c, d, a, x[i + 0], 20, -373897302)

    a = gg(a, b, c, d, x[i + 5], 5, -701558691)

    d = gg(d, a, b, c, x[i + 10], 9, 38016083)

    c = gg(c, d, a, b, x[i + 15], 14, -660478335)

    b = gg(b, c, d, a, x[i + 4], 20, -405537848)

    a = gg(a, b, c, d, x[i + 9], 5, 568446438)

    d = gg(d, a, b, c, x[i + 14], 9, -1019803690)

    c = gg(c, d, a, b, x[i + 3], 14, -187363961)

    b = gg(b, c, d, a, x[i + 8], 20, 1163531501)

    a = gg(a, b, c, d, x[i + 13], 5, -1444681467)

    d = gg(d, a, b, c, x[i + 2], 9, -51403784)

    c = gg(c, d, a, b, x[i + 7], 14, 1735328473)

    b = gg(b, c, d, a, x[i + 12], 20, -1926607734)



    a = hh(a, b, c, d, x[i + 5], 4, -378558)

    d = hh(d, a, b, c, x[i + 8], 11, -2022574463)

    c = hh(c, d, a, b, x[i + 11], 16, 1839030562)

    b = hh(b, c, d, a, x[i + 14], 23, -35309556)

    a = hh(a, b, c, d, x[i + 1], 4, -1530992060)

    d = hh(d, a, b, c, x[i + 4], 11, 1272893353)

    c = hh(c, d, a, b, x[i + 7], 16, -155497632)

    b = hh(b, c, d, a, x[i + 10], 23, -1094730640)

    a = hh(a, b, c, d, x[i + 13], 4, 681279174)

    d = hh(d, a, b, c, x[i + 0], 11, -358537222)

    c = hh(c, d, a, b, x[i + 3], 16, -722521979)

    b = hh(b, c, d, a, x[i + 6], 23, 76029189)

    a = hh(a, b, c, d, x[i + 9], 4, -640364487)

    d = hh(d, a, b, c, x[i + 12], 11, -421815835)

    c = hh(c, d, a, b, x[i + 15], 16, 530742520)

    b = hh(b, c, d, a, x[i + 2], 23, -995338651)



    a = ii(a, b, c, d, x[i + 0], 6, -198630844)

    d = ii(d, a, b, c, x[i + 7], 10, 1126891415)

    c = ii(c, d, a, b, x[i + 14], 15, -1416354905)

    b = ii(b, c, d, a, x[i + 5], 21, -57434055)

    a = ii(a, b, c, d, x[i + 12], 6, 1700485571)

    d = ii(d, a, b, c, x[i + 3], 10, -1894986606)

    c = ii(c, d, a, b, x[i + 10], 15, -1051523)

    b = ii(b, c, d, a, x[i + 1], 21, -2054922799)

    a = ii(a, b, c, d, x[i + 8], 6, 1873313359)

    d = ii(d, a, b, c, x[i + 15], 10, -30611744)

    c = ii(c, d, a, b, x[i + 6], 15, -1560198380)

    b = ii(b, c, d, a, x[i + 13], 21, 1309151649)

    a = ii(a, b, c, d, x[i + 4], 6, -145523070)

    d = ii(d, a, b, c, x[i + 11], 10, -1120210379)

    c = ii(c, d, a, b, x[i + 2], 15, 718787259)

    b = ii(b, c, d, a, x[i + 9], 21, -343485551)



    a = safe_add(a, olda)

    b = safe_add(b, oldb)

    c = safe_add(c, oldc)

    d = safe_add(d, oldd)

  }

  return [a, b, c, d]

}



/*
 * Convert an array of little-endian words to a hex string.
 */

function binl2hex(binarray) {

  var hex_tab = "0123456789abcdef"

  var str = ""

  for (var i = 0; i < binarray.length * 4; i++) {

    str += hex_tab.charAt((binarray[i >> 2] >> ((i % 4) * 8 + 4)) & 0xF) +

      hex_tab.charAt((binarray[i >> 2] >> ((i % 4) * 8)) & 0xF)

  }

  return str

}



/*
 * Convert an array of little-endian words to a base64 encoded string.
 */

function binl2b64(binarray) {

  var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

  var str = ""

  for (var i = 0; i < binarray.length * 32; i += 6) {

    str += tab.charAt(((binarray[i >> 5] << (i % 32)) & 0x3F) |

      ((binarray[i >> 5 + 1] >> (32 - i % 32)) & 0x3F))

  }

  return str

}



/*
 * Convert an 8-bit character string to a sequence of 16-word blocks, stored
 * as an array, and append appropriate padding for MD4/5 calculation.
 * If any of the characters are >255, the high byte is silently ignored.
 */

function str2binl(str) {

  var nblk = ((str.length + 8) >> 6) + 1 // number of 16-word blocks  

  var blks = new Array(nblk * 16)

  for (var i = 0; i < nblk * 16; i++) blks[i] = 0

  for (var i = 0; i < str.length; i++)

    blks[i >> 2] |= (str.charCodeAt(i) & 0xFF) << ((i % 4) * 8)

  blks[i >> 2] |= 0x80 << ((i % 4) * 8)

  blks[nblk * 16 - 2] = str.length * 8

  return blks

}



/*
 * Convert a wide-character string to a sequence of 16-word blocks, stored as
 * an array, and append appropriate padding for MD4/5 calculation.
 */

function strw2binl(str) {

  var nblk = ((str.length + 4) >> 5) + 1 // number of 16-word blocks  

  var blks = new Array(nblk * 16)

  for (var i = 0; i < nblk * 16; i++) blks[i] = 0

  for (var i = 0; i < str.length; i++)

    blks[i >> 1] |= str.charCodeAt(i) << ((i % 2) * 16)

  blks[i >> 1] |= 0x80 << ((i % 2) * 16)

  blks[nblk * 16 - 2] = str.length * 16

  return blks

}



/*
 * External interface
 */
// create md5，调用：var str = md5.hexMD5('name')
function hexMD5(str) {
  return binl2hex(coreMD5(str2binl(str)))
}

function hexMD5w(str) {
  return binl2hex(coreMD5(strw2binl(str)))
}

function b64MD5(str) {
  return binl2b64(coreMD5(str2binl(str)))
}

function b64MD5w(str) {
  return binl2b64(coreMD5(strw2binl(str)))
}

/* Backward compatibility */

function calcMD5(str) {
  return binl2hex(coreMD5(str2binl(str)))
}

module.exports = {
  md5: hexMD5
}